Low-pressure fuel injection devices for internal combustion engines



May 5, 1964 3,132,193

L. PERAS LOW-PRESSURE FUEL INJECTION DEVICES FOR. INTERNAL COMBUSTION ENGINES Filed Dec. 11, 1959 2 Sheets-Sheet 1 INVENTOR Lucvau Deans MM, 10 w WM ATTORNEYS May 5, 1964 3,132,193

' L. PERAS LOWPRESSURE FUEL INJECTION DEVICES FOR Filed Dec. 11, 1959 INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Laden Far-15 United States Patent ()fiFice 3,132,193 Patented May 5, 1964 3,132,193 LOW-PRESSURE FUEL INJECTION DEVICES FQR INTERNAL COUSTION ENGINES Lucien Pras, Billancourt, France, assignor to Regie Nationale des Usines Renault, Biilancourt, France Filed Dec. 11, 1959, Ser. No. 859,026

Claims priority, application France Dec. 16, 1958 11 Claims. ((31. 261-134) The present invention relates to low-pressure fuel injection devices for internal combustion engines.

Devices of this character are already known wherein the fuel pressure is obtained by means of an auxiliary pump of the blade, gear or centrifugal type, the output adjustment being effected by throttling the fuel delivered from the pump. A system proposed by the applicant in a prior patent application Ser. No. 774,192 of November 17, 1958, now abandoned, consists of pressurizing a unit including a conventional-type fuel feed pump, for example a self-regulating fuel pump incorporating a gauged spring and responsive to a lever actuated by the camshaft of the engine, and a centrifugal pump disposed in series with the aforesaid fuel feed pump. This centrifugal pump may be adapted if desired to its functions by certain arrangements consistent therewith. Thus, in order to prevent the leaks usually at the bearings of the centrifugal pump from occurring permanently irrespective of the pump speed, the fuelinlet is not coincident with but somewhat spaced from, the wheel axis. Moreover, fuel leaksoccurring through the pump bearings when the pump revolves at a relatively low speed are directed to a pump chamber connected through a pipe line to the fuel tank. In the system proposed in this prior patent application the member for .throttlingthe liquid stream (which consists of a needle valve) opens directly into the inlet passage so as to utilize the whole of the energy available for carrying out the mechanical atomization. However, this available energy, although sufficient athigh speeds, is inadequate at low speeds and under reduced load conditions for producing directly the desired mechanical atomization.

Another device proposed by the applicant in another prior patent application Serial Number 853,202, filed on November 16, 1959, now Patent No. 3,003,755, makes it possible to use this available energy for creating an intimate vapor-liquid mixture with a secondary air supply, prior to introducing the atomized mixture into the main air stream or induction circuit.

On the other hand, such vapor-liquid mixture systems are .well known not only in low-pressure fuel injection methods but also in conventional-type carburetors, whereproblems involving an adjustment of the proportions of a liquid/gas mixture.

The device forming the subject-matter of the patent application Serial Number 853,202, filed onNovember 16, 1959, now Patent No. 3,003,755, by the applicant consists of a slide valve associated with a frusto-conical chamber the large base of which is movable on the slide-face of a distributor unit or block. The chamber has a gas inlet and a fuel or liquid inlet. The displacement of the slide valve alters the cross-sectional area of the liquid inlet orifice without appreciably modifying the cross-sectional area of the gas passage. The liquid and gaseous components are projected by the kinetic energy of either the liquid alone, or both the liquid and gas components, into the frusto-conical chamber with the slide valve acting as a vapor-liquid mixture chamber. The small base of this chamber constitutes the outlet orifice for the vapor-liquid mixture. To permit its displacement, the slide valve is formed along its top and bottom faces with grooves par allel to the slide-face and engaged by blades inclined in relation to said slide face, whereby the component tending to press the slide valve against its slide-face will be a constant fraction of the reaction effort produced during this dis placement; one of these blades receives the predetermined pressure from a tension spring and the other or driving blade which causes the displacement of the slide valve is actuated by a lever responsive in turn to an adjustment screw.

In the patent application Serial Number 853,202 on November 16, 1959, now Patent No. 3,003,755, by the applicant, only a very broad utilization of the device is contemplated, without any description of anautomatic system in which it could be incorporated.

Now it is the object of the present invention to provide means for permitting a more specific application of this device whereby, in an internal combustion engine provided with a low-pressure injection system, the optimum conditions of use of the aforesaid device may be obtained.

As a matter of fact, instead of utilizing a manually controlled output device as proposed in the aforesaid patent application Ser. No. 853,202, now Patent No. 3,003,755,

1 the present invention provides means whereby:

(1) The fuel under pressure is delivered from a conventional-type feed pump associated in series with a centrifugal pump with a view to ensure a fuel pressure increasing. with the engine speed (as described in the 1 aforesaid patent application Ser. No. 774,192, now

in three ports are always provided, one for the supply of secondary air, another for the supply of fuel, and another for delivering the mixture. In a carburetor, notably, the idling circuit is established under these conditions and the energy is supplied by the vacuum from the induction pipe. When this vacuum is'relatively high, a highly vapor-liquid mixture is obtained; unfortunately, the idling circuit of a carburetor is unsuitable for properly metering the components of the vapor-liquid mixture and providing a constant efliciency throughout the range of speeds and loads.

. It is the essential feature of the device forming the subject-matter of the patent application Serial Number 853,- 202, filed on November 16, 1959, now Patent No. 3,003,-- 755, by the same applicant to provide a vapor-liquid mixing device'based on the same principle but adapted to exert an adjustment function, the vapor-liquid mixture chamber consisting of a slide valve the movements of which, in relation to its slide-face, are adapted to vary at will the cross-sectional area of the fuel delivery orifice. This system is concerned more particularly with air/fuel mixtures, but the proposition is also applicable to any abandoned).

- (2) The variation in the output of the slide valve is controlled by means of a vacuum-responsive diaphragmtype capsule receiving on'one face of the diaphragm the absolute pressure prevailing downstream of the accelerator throttle and on the other face the atmospheric pressure. The resulting thrust is transmitted to a main lever acting upon the aforesaid slide-valve control blades;

(3) This output variation is not linear, for the spring blade,.whereby the position of the slide valve is adjusted as a function of the vacuum, engages during its bending movement another bearing point adapted to increase its stiffness;

(4) The fuel supply is cut off completely each time the accelerator pedal is released, provided that the speed of the vehicle is sufficient. This result is obtained by. providing another vacuum-responsive diaphragm capsule receiving on one face of its diaphragm the absolute pressure prevailing downstream of the accelerator throttle which is compensated by a flexible and weak spring, and on the other face the same vacuum adapted to he suddenly replaced by-the atmospheric pressure due to the provision of a balanced valve system becoming operative when the absolute pressure at the valves is equal to or lower I than a predetermined value;

An easy-start device will firstly lift to enable an additional quantity of air to be introduced for increasing the quantity of the air drawn through the device even if the accelerator throttle were fully closed, this additional supply of air being adapted, by exerting a pressure on a lever interposed in the control means of said slide valve, to increase the richness of the mixture;

(6) A device consisting of a sealed metal bellows communicating with the fuel inlet and adapted to transmit the pressure from this fuel to the'main lever with a view to producing a slight change in the condition of equilibrium of this lever and decreasing the cross-sectional area of the passage controlled by said slide valve when the fuel pressure is relatively high, that is, when the engine rotates at very high speed, thereby decreasing the quantity of fuel delivered per cycle as the filling of the engine with air decreases;

(7) Although the atomization effected by this device is such that, under reduced load conditions, the same specific fuel consumption is obtained with variations in the richness of the mixture which range from about to a temperature and altitude correction is provided whereby the first vacuum-responsive diaphragm capsule set forth in paragraph (2) hereinabove is replaced by a vacuum case containing a sealed,'pleated metal bellows or capsule containing a reference or pilot mass of air.

A specific form of embodiment of this low-pressure fuel injection system for internal combustion engines is described hereafter by way of example with reference to the attached drawings forming part of this specification and wherein:

FIGURE 1 is a longitudinal section of the metering device;

FIGURE 2 isa cross-section of the device which is taken upon the line 2-2 of FIG. 1 but illustrating a whole cross section ofthe device and with certain parts broken away;

FIGURE 3 is a modified form of embodiment of one portion of the device illustrated in FIG. 1, wherein a metal bellows containing pilotair is substituted for the atmospheric vacuum capsules;

FIGURE 4 is a diagram showing the values of the output per cycle as a function of the absolute pressure prevailing at the valves of the engine; and

FIGURE 5 is a detail view illustrating the relationship of the slide valve and orifice in a partially closed condition.

Referring first to FIGS. 1 and 2 of the drawings, the

reference numeral 1 designates the fixed metal blockto which fuel and air supply lines are connected to passages 2 and3 respectively, the air passage 3 being connected to a pair of symmetric supply lines (see FIG. 2). V

The fuel inlet passage is formed at its outlet end with a restricted jet-forming orifice 4 opening, like the air passage 3, on the slide face 5. A slide valve 6 engages this slide-face 5 and comprises a vapor-liquid mixing chamber 7 shown as having a straight frusto-conical configuration in this example but adapted to have an oblique frustoconical form or a non-conical form of revolution.

The circle 8 constituting the large base of the cone partially closes the fuel jet 4. Under these conditions the cross-sectional area of the air inlet orifice will vary only moderately, so that the ingress of air is in no case retarded irrespective of the position of the slide valve. The circle 10 constitutingthe small base of the cone acts at the same time as the outlet orifice for the air/ fuel mixture.

The slide valve 6 is formed with upper and lower grooves l1, l2 engaged by blades 13, M respectively, these blades forming the same angle with the slide-face and urging the slide valve 6 into engagement with the slide face 5. The upper blade 13 is urged by a spring blade 15 bearing on the one hand on a knife-edge 16 and on'the other hand on an adjustment screw 17. This spring 15 is formed with a notch 18 and thus prevented from slipping laterally. The adjustment screw 17 may 4 be locked in the selected position of adjustment by a lock nut 19.

Another screw 22 becomes a second bearing point when the blade 15 exceeds a certain amount of flexure, the first bearing point 17 becoming inoperative in this case. This screw 22 is also provided with. a lock nut 23.

The blade 14 is urged upwards by a lever 20 fulcrumed about a knife-edge formed on a blade 21 secured by a screw 28 on the metal peripheralframe 24 constituting the body ofthe metering device. A vacuum chamber is thus formed by this peripheral frame 24 and by a pair of side plates 29, 35) on which the block 1 is also secured and between which the blades of the movable assembly, lever 20, lower blade 14, slide valve 6, upper blade 13 and spring 15 are slidably fitted. This structure of the metering device is held in position on a tube 31 mounted on engine 94 having an accurately calibrated bore, a smooth inner wall, and an external fiat face 32 on which the front face of the metering device is secured by a pair of plates 33 fastened by screws 34.

This tube 31 is provided with a conventional butterfly throttle 25 pivotally mounted on a transverse pin 35.

Downstream of the butterfly .25 are various holes formed through the wall of the tube, that is, a first hole 36 through which the nozzle of the slide valve vaporliquid mixture chamber projects into the tube passage and is movable vertically according to its adjustment, another hole 37 for increasing the total cross-sectional area of the passage, and finally a hole 38 for recovering in the induction pipe any fuel leaks occurring in the inner space of the metering device.'

The tube 31, along the greater part of its height and more particularly in the region where the air/ fuel mixture is sprayed by the device, is surrounded by a jacket 39 forming a passage in which the water from the cooling system of the engine is circulated through inlet and outlet connections 93.

As a matter of fact, it is essential that heat for com- 7 pensating the latent vaporization heat be applied to the region where the maximum atomization is to take place. A hole 40 having a conical inner end 41 is formed through the lever 20. This conical end 41 receives the v substantially spherical tip of a rod 42 rigid with the diaphragm 43 of a vacuum responsive capsule 44screwed in the frame 24. On the atmospheric side of. the diaphragm a spring 45 provides a pre-stress transmitted to the spring blade 15 through the medium of the lever 20.

Registering with a notch 46 formed in this lever 20 but not contacting same under normal conditions is the spherical tip of another rod 47 rigid with the diaphragm 48 of a vacuum capsule 49 also screwed in the peripheral frame of the metering device. On the same side as the rod 47 is a relatively flexible spring 50 bearing against the inner base of the capsule body and exerting a nearly constant thrust against the diaphragm which is equivalent to 5 57 by a spring 59 disposed inside the valve 58. The

vacuum transmitted through the oblique passage 56 is effective inside this valve 58.

In a modified form of embodiment the capsule 44 may be replaced by a case 60 screwed in the same manner in the body of the device but containing a metal bellows 61 welded in a fluid-tight manner on a pair of plates 62, 63

and containing a mass of reference or pilot air. The

plate 63 is secured on one wall of the body and the other plate 62 is rigid with the rod 42 (see FIG. 3).

Welded inside the block 1 is a small sealed metal bellows 64 closed at its lower end by a small plate 65'and communicating through the orifice 66 with the passage 2.

This bellows is thus filled with fuel, and its elasticity makes its capacity completely responsive to the fuel pressure. It bears through the small plate 65 upon the upper face of leverZtl. v

The frame of the metering device has secured on its lower portion and in a fluid-tight manner a member 67 73 with the delivery. side of a centrifugal pump 74 of a type similar to the constructiondescribed and illustrated in the aforesaid patent application Serial No. 774,192, now abandoned (see FIG. 2), this fuel pump being fed from the tank 76 through the conventional fuel pump. 75. The valve 68 is adapted to connect the passages 80, 81 from the atmosphere with the inner vacuum'space of the metering device, and the head of the valve 68 is adapted to abut against the lever 20.

I The injection device described hereinabove operates as follows: g

' Case I.-Engine Under Full Load The butterfly 25 is wide open. The pressure prevailing within the induction manifold of which the tube 31 isan integral part and within the inner vacuum space of the metering device is substantially equal to the atmospheric pressure; the spring 45 transmits through the rod 42 a certain pressure to the conical bottom 41 of lever 20 and the latter, by-rotating slightly about its fulcrum (the knifeedge 21) applies a thrust to the lower blade 14 and therefore to the slide valve 26 and therefore to the opposite or upper blade 13- engaging the spring blade 15 reacting on the knife-edge 18 and on the inner end of screw 17. The flexure of this spring determines a position of equilibrium of the slide valve 6', whereby it reduces the crosssectional outlet area of the jet 4 to one fractionof acircle. This area may be. adjusted by rotating the screw 17, where? after this screw is locked in positionby the lock nut 19. Thus, for a given engine speed the pressure in the line 73, passageZ andthrough the jet 4 is positively and properly defined.v The proportion of the fuel output, to the air output is thus adjusted only by means of the screw 17.

When thespeed varies, the butterfly remainingistill wide open, the pressure in the fuel line 73 varies as the square of the. angular speed or the rpm. of the pump 74. In

the case ofstill lower and average speeds, this pressure will remain relatively moderate in absolute value and the pressure exerted by the bellows 64 on the. lever 20 will also be moderate so as to change only slightly the position of the slide valve 6,,so that the cross-sectional area of jet 4 will remain practically constant. Thus, the fuel output will increase in proportion to'the engine speed, and as the same applies to the air output the proportion will be maintained.

If the engine speed becomes very high, the rate at which the engine. is filled with air will decrease, but on the other hand the fuel pressure becomes very high. The action exerted by the bellows 64 on the equilibrium of lever 2.0 will be considerable and the slide valve 6 will move in the direction to reduce the free cross-sectional area of the jet d. Thus, the curve of the output per cycle as a function of speed may be regulated in conformity with the curve representing the rate of filling of the engine with air, witha view to maintain the desired richness of the mixture. a I

The fuel jet is sprayed into the frusto-conical space 7 with a moderate incidence and flows through the atomizing orifice 10 while drawing through the: orifice 3 a certain quantity of air which will be termed secondary air for the purposes of this invention, this secondary air forming with the liquid fuel a rather rough vapor-liquid mixture which however is completed in the tube 31 due to the action of the incoming stream of primary air 27 as a consequence of the suctional effort from the engine.

The fuel particles that cannot be prevented from adhering to theinner surface of the tube 31 will be vaporized more easily due to the temperature of this surface which is maintained at a sufficient value by the water jacket surrounding same.

Case II.Engz'ne Under Reduced Load When the butterfly 25 is gradually closed, the absolute pressure in the passage 31- attains a value lower than the atmospheric value and, through the medium of the orifices 36, 37, and of the sealed space of the metering device, the diaphragm 43 receives from the left-hand side an additional thrust due to the pressure differential, and

. pushes the lever 20 and the other movable components with a greater force. Thus, the cross-sectional area of the jet 4, which is controlled by the slide valve 6, is further reduced. I

As long as this pressure remains close to the atmospheric value, the law governing the slide valve movements and therefore the output law (for a given speed) corresponds to the straight line 77 of the diagram (FIG. 4). When the absolute pressure becomes lower (that is, inferior to p), which means that the vacuum increases in the tube 31, the ilexure of the spring blade 15 is accentuated to the extent of causing same to engage the second bearing point consisting of the inner end of screw 22, the position of this screw being adjusted accordingly. Thus, the spring blade 15 leaves the tip of the first screw 17 and its stiffness is increased considerably, so that the variation in the output will become consistent with the law shown by the straight line 78 of the diagram of FIG. 4. V

The pressure prevailing within the cone 7 is substantially equal to atmospheric pressure since atmospheric air is supplied to cone 7 through orifice 5 and since outlet orifice 10 which is smaller than orifice 5 performs a restricting function on the air at Substantially atmospheric pressure which passes through the cone 7. This restricting function of orifice 10 serves to partially shield the inner portion of cone 7 from the pressure prevailing in the tube 31. Under these conditions, a substantial air output flows through the cone 7 and impinges against the fuel jet so as to form therewith .a very intimate vapor-liquid mixture, the higher the vacuum (that is, the lower the engine load), the higher the velocity of flow of this air. The atomization thus obtained is suchthat the vaporliquid mixture is carried along by the air stream '27 wtih the minimum quantity of fuel particlesadheringon the inner wall of tube 31. l

Case IlI.-Fuel Cut-01f Duringthe operation under the conditionsset forth in Sections I and I1 hereinabove, vacuum is alsoproduccd on either side of the diaphragm 48, that is, on its lower face because the capsule communicates directly with the inner space of the metering device, and on its upper face through the pipe 52, circular recess 53, jet 55 and passage 56. Thevalve 58 is urged by its spring 59 against the edge of orifice 57 and no air is admitted from the external atmosphere. Under these conditions, the equilibrium of the diaphragm 48 would be neutral, but the spring 50 urges the assembly of rod 47 and diaphragm 48 against the abutment51; therod 47 is spacedsufficiently from the notch 46 of lever 20 to avoid any interference with the proper operation of the movable assembly.

When the absolute pressure is further reduced and attains the value p (FIG. 4 the spring 59 cannot compensate by itself the resultant thrust exerted on the section of orifice 57 and the valve 58 begins to open. Now the atmospheric pressure acts upon the cross-section corresponding to the outer guiding diameter of valve 58 which is slightly greater than that of theorifice 57. Thus,

the valve 58 is positively lifted and the atmospheric pressure is effective in the circular recess 53, pipe 52 and against the upper face of diaphragm 48. But it will not substantially alter the pressure under the valve 58 since the section available through the restricted orifice 55 is considerably smaller than that of passage 56.

The rod 47 rigid with the diaphragm 48 is thus moved downward by a relatively great force since the difference between the atmospheric pressure and the pressure p defined hereinabove is several times greater than the thrust exerted by the spring 50. This rod 47 will thus strike against the notch 46 of lever 20. Lever 20 will be jarred and causes the elastic lever 15 to be tilted, and the movement of the slide valve 6 will close the jet completely.

The fuel output is thus cut-off completely, as shown at 79 (FIG. 4). Of course, the pressure p which is the selected limit in this example is the pressure equal to the pressure when the drivers foot is released from the accelerator pedal so that the engine is driven by the vehicle, as in the case of long downhill runs or during decelerations in town driving. In this case it is advantageous to cut off the fuel supply completely, but this is convenient only if the following two conditions are met:

(a) If the vehicle and the engine slow down to a sufficient degree and if the engine is drivingly disconnected from the vehicle by shifting the transmission to neutral, the fuel supply must be restored so that the engine may preserve its idling speed without necessitating any intervention from the driver. In the system according to the invention, as the speed is reduced, i.e., when the engine slows down, for a given position of the butterfly, the absolute pressure that prevails in the vacuum chamber formed by the peripheral frame 24, the side plates 29, 30

8 shank 69 of valve 68 in the easy-start device has been lifted so that this valve 68-Wl1l cause the inner space of the metering device to communicate with the external atmosphere through the passages 80 and 81, and a sulficient volume of air is sucked through the tube 31 and orifices 36, 37 by the engine. At the same time, the valve 68 moves the lever in a direction tending to increase the cross-sectional area of the jet 4, so that the fuel output per cycle will become greater than the normal output, and therefore the richness will also be greater than the normal richness. Since a sufficient quantity of air/ fuel mixture is introduced in spite of the closing of the butterfly 25, the engine operates normally. The manner in which the shank 69 of valve 68 is actuated is not set forth and illustrated in detail herein; this movement may be obtained for example by means of a return spring (not shown) associated with the sheath of a Bowden wire device 91, and a manual control device 90, conand the flat face 32, increases to a value p" at which point the force exterted by the atmospheric pressure upon the section of valve 58 corresponds to its exterior guiding diameter becomes smaller than the force exerted by Spring 59 so that the valve will be closed by said spring. From the moment valve 58 seats against orifice 57, the force of the atmospheric pressure acting on valve 58 is reduced because it is only exerted upon that section of the valve 58 corresponding to the diameter of orifice 57 which has an area less than that of the exterior guiding diameter of the valve.

The valve 58 thus isolates or cuts off from the atmosphere the circuit including the pipe 52, the circular recess 53, the passage 54, the restricted orifice 55, and the passage 56 so that the vacuum is immediately restored in the pipe 52. The pressures are balanced on either side of the diaphragm 48 and the spring 50 will rapidly urge the rod 47 against the abutment 51, thus enabling the lever 20 to resume its normal position corresponding to the normal absolute pressure and to restore the output as shown by the curve 78.

(b) It is a must that at any moment when the drivers foot depresses the accelerator pedal the engine pick up immediately, without delay. The accelerator is connected to the shaft of the valve 25. The description of the above sub-section (a) remains applicable with the difference that the absolute pressure p will abruptly resume the atmospheric value and that all the movements and actions set forth take place more rapidly. During the period when jet 4 is closed by valve 6, the fuel remaining in passage 2 is maintained under pressure by pump 74 which is continuously driven by the engine at a speed corresponding to the engine speed. Therefore, when valve 6 uncovers jet 4, the pressurized fuel in passage 2 is instantaneously discharged therefrom and supplied to cone 7 and orifice 10.

of the throttle position. If the butterfly is left in its closed position, when the driver depresses the starter switch, the

nected to an engine starter 95 as in the case of conventional easy-start systems wherein the manual control device may be moved in a left-hand or right-hand direction, when looking at FIGURE 1, but other means such as a bimetallic strip acting as a spring in the cold state, or an elastic capacity expanding under the influence of a fluid or as a consequence of an increase in the pressure of saturating steam the liquid of which is situated at a suitably selected point of reference, may be used.

When the engine temperature increases, the manual control device 90 is moved in a right-hand direction when looking at FIGURE 1 to partially close valve 68 whereby the richness begins to decrease until the valve 68 is separated from the level 20, whereafter the richness is restored to its normal value. The air passage remains open during a few moments until the valve 68 rests completely on its seat 67, but this is immaterial.

On the contrary, if the butterfly 25 is maintained wide open, the first lifting movement of this valve 68 will not change in any appreciable proportion or ratio the quantity of air introduced into the engine, but the pressure exerted by this valve 68 on the lever 20 increases the richness of the mixture as in the preceding case, even under full load conditions.

Case V.--Temperature and Altitude Correction Assuming that the case 60 of FIG. 3 were substituted for the capsule 44, the absolute pressure is established around the bellows 61 while internally of this bellows the pressure is substantially the initial one, that is, close to the original atmospheric value which is independent of the present atmospheric pressure. It is obvious that an increase in the ambient temperature will cause an expansion of the gas container in the zone formed by the diaphragm 61 resulting in the appearance of a thrust force on the rod 42. If the spring 15 had only one bearing point, the output correction thus accomplished as a consequence of a variation in the temperature and altitude would be independent of the load, whereas it should normally be proportional thereto, but the use of two successive bearing points for different loads, that is, of two difierent'output laws 77 and 78, provides a different temperature and altitude correction for each of these two laws, thus affording a sufiicient approach for the necessary correction value under all load conditions.

In the foregoing, reference is made several times to atmospheric air intakes, such as the air led through the inlet 26, the easy-start air delivered through the orifice 81 and the air introduced through the orifice 57 for cutting off the fuel supply. Of course, these various air intakes may be assembled into an inlet pipe upstream of the butterfly 25 so as to be maintained substantially at the atmospheric value with the additional advantage resulting from the presence of an air filter as usually provided at the inlet end of the induction manifold, although this arrangement has not been shown in the drawmgs. t

9 I claim:

1. A low pressure fuel injection device for internal combustion engines, comprising an air induction tube having an accelerator ibutterfly mounted therein, a sealed casing mounted on said induction tube and having a portion downstream of the accelerator butterfly, said tube having an opening downstream of said butterfly in communication with the interior of said casing, a distributor block having slide face means and fixedly mounted in said casing adjacent said opening, secondary air duct means communicating with the atmosphere, extending through a Wall of said casing and said block and opening in said slide face means, a fuel pump, fuel supply means connected to said pump, duct means for pressurized fuel extending through said wall and said block and opening in said slide face means adjacent said air duct means, conduit means interconnecting said fuel pump and said duct means for pressurized tfuel, slide valve means overlying said slide face means and having a chamber communicating with said fuel duct means and said secondary air duct means, said chamber terminating in a discharge orifice remote from said slide face means, said slide valve means projecting with said dischange orifice through said opening whereby an air-fuel mixture can be discharged during operation through said orifice from said chamber into said induction tube, means mounting said slide valve means for movement relative to said distributor block to vary the effective discharge cross section of said fuel passage, spring device means and lever means between which said slide valve is supported, and automatic control means engaging said lever means to control the position of said slide valve means and vary the richness of the air-fuel mixture.

2. The device of claim 1, wherein said lever means is disposed in said casing and said automatic control means includes a vacuum responsive means, and second duct means inter-communicating said vacuum responsive means and said induction tube downstream of the accelerator butterfly, whereby the air-fuel ratio increases responsive to an increase in vacuum.

3. The device of claim 1, wherein said control means includes a means operable in response to a reduction in pressure within said induction tube downstream of the accelerator butterfly, a restricted orifice defined by said casing in communication with the interior of said casing, said pressure responsive means including a spring loaded diaphragm having a first surface exposed to the pressure Within said induction tube downstream of the accelerator butterfly and an opposite surface, third duct means intercommunicating said restricted orifice and said opposite surface, and means for opening said opposite surface to the atmosphere, whereby the air-fuel ratio increases when said opposite surface is exposed to atmospheric pressure.

4. The device of claim 1, wherein said spring means comprises a spring blade mounted in said casing and having a first end and a second end, means pivotally mounting said spring blade proximate said first end, means proximate said second end interconnecting said slide valve means and said blade, and two successively engaged bearing means for engagement by said spring blade to vary the action of said spring blade.

5. The device of claim 1, wherein said engine includes starting means, air supply means, inlet valve means mounted in said casing and connected to said air supply means, passage means intercommunicating said inlet valve means and said induction tube, said inlet valve means being operable responsive to said starting means to supply air to said induction tube.

6. The device of claim 1, wherein said induction tube is provided with a water jacket opposite to said slide valve means, said water jacket having heated fluid inlet and outlet means for supplying heat to the air-fuel mixture.

7. The device of claim 1, wherein said control means includes a bellows means in communication with said fuel duct means and being operable to vary the position of said slide valve means in response to variations in fuel pressure within said fuel duct.

8. The device of claim 1 wherein said control means includes a sealed bellows means containing a mass of air and acted upon by temperature and atmospheric pressures.

9. The device of claim 1 wherein said control means includes means operable in response to a reduction in pressure Within said induction tube downstream of the accelerator butterfly to a predetermined pressure to move said slide valve means to a fuel'passage closing position.

10. The device of claim 3 wherein said last mentioned means includes a spring loaded valve means acted upon by the pressure Within said induction tube downstream of the accelerator butterfly.

11. The device of claim 1 wherein said control means is secure-d to said casing.

References Cited in the file of this patent UNITED STATES PATENTS 134,372 Frank Dec. 31, 1872 2,680,605 Bracke June 8, 1954 2,786,659 Mennesson Mar. 26, 1957 2,840,359 Cornelius June 24, 1958 2,877,998 Cornelius Mar. 17, 1959 2,894,829 Harrison et a1. July 14, 1959 

1. A LOW PRESSURE FUEL INJECTION DEVIDE FOR INTERNAL COMBUSTION ENGINES, COMPRISING AN AIR INDUCTION TUBR HAVING AN ACCELERATOR BUTTERFLY MOUNTED THEREIN, A SEALED CASING MOUNTED ON SAID INDUCTION TUBE AND HAVING A PORTION DOWNSTREAM OF THE ACCELERATOR BUTTERFLY, SAID TUBE HAVING AN OPENING DOWNSTREAM OF SAID BUTTERFLY IN COMMUNICATION WITH THE INTERIOR OF SAID CASING, A DISTRIBUTOR BLOCK HAVING SLIDE FACE MEANS AND FIXEDLY MOUNTED IN SAID CASING ADJACENT SAID OPENING, SECONDARY AIR DUCT MEANS COMMUNICATING WITH THE ATMOSPHRE, EXTENDING THROUGH A WALL OF SAID CASING AND SAID VLOCK AND OPENING IN SAID SLIDE FACE MEANS, A FUEL PUMP, FUEL SUPPLY MEANS CONNECTED TO SAID PUMP, DUCT MEANS FOR PRESSURIZED FUEL EXTENDING THROUGH SAID WALL AND SAID BLOCK AND OPENING IN SAID SLIDE FACE MEANS ADJACENT SAID AIR DUCT MEANS, CONDUIT MEANS INTERCONNECTING SAID FUEL PUMP AND SAID DUCT MEANS FOR PRESSURIZED FUEL, SLIDE VALVE MEANS OVERLYING SAID SLIDE FACE MEANS AND HAVING A CHAMBER COMMUNICATING WITH SAID FUEL DUCT MEANS AND SAID SECNDARY AIR DUCT MEANS, SAID CHAMBER TERMINATING IN A DISCHARGE ORIFICE REMOTE FROM SAID SLIDE FACE MEANS, SAID SLIDE VALVE MEANS PROJECTING WITH SAID DISCHARGE ORIFICE THROUGH SAID OPENING 